The eye of the marine gastropod, Strombus luhuanus, is anatomically well developed, visually important, and exhibits complex light-evoked electrical activity. Following amputation, a new and apparently normal eye is regenerated. The proposed research concerns 1) the mechanisms underlying the processing of visual information in the mature eye of Strombus, and 2) ontogeny of these mechanisms during regeneration of the eye. It focuses on a variety of problems concerned with photoreceptor excitation and inhibition, neural interactions between retinal elements, and the neural coding of visual information in the retinas of mature and regenerating eyes. Electrophysiological recording and stimulating techniques, combined with methods for photic stimulation, will be used to examine extracellular potentials from the retina and optic nerve, and intracellular electrical events from single retinal neurons. Anatomical studies employing light and electron microscopy and techniques for staining single neurons with intracellular dye will accompany the electrophysiological investigations. The proposed research promises to increase our understanding of the mechanisms involved in visual information processing, and to elucidate the mechanisms underlying the development of a relatively complex eye and of sense organs and nervous systems in general.